Acidproof composition



106. COMPOSITIONS, txammow COATING R PLASTIC. 9

n A .l t :l: Patented Apr. 23, 1935 r UNITED STATES PATENT OFFICE ACIDPROOF COMPOSITION Charles R. Kuzell, John R. Marston, and Francis X. Mooney, Clarkdale, Ariz., assignors to United Verde Copper Company, Clarkdale, Aria, a corporation of Delaware No Drawing. Application September 23, 1932, Serial No. 634,562

r 8 Claims. (Cl. 106-40) This invention relates to acid-proof composis en he C mm experience, (See P 130 tions and has for an object the provision of im- S b e silicates In Industry The proved acid proof cements, mortars and struc- Chemical Catalog C 1923) to encounter tures. More particularly, the invention contemgreat difliculty in t e C nst Of a y,

5 plates the provision of improved cements a d brick work or cast masses because of this ex- 5 mortars of the water-glass or sodium silicate type e y W Setting which y he deseribed as for use in the production of acid proof structhe lack of a pronounced initial set. The need tures. The invention further contemplates the r initial Setting d i c n l h s l n n P ovision of an improved method of forming id felt in the construction of acid proof structures.

1 proof structures. While others have attempted to improve acid Sodium silicate glass products may be considproof cements, mortars, and aggregates for acid ered to be solid solutions of silica in the meta- P Struc ure by e addition of agents which silicate of soda, NazSiOa, the ratio of soda to silica will eu a e t e Sodium hydIOXide liberated y (NazO to S102) varying within wide limits, the hydrolysis of the soluble silicate, the previous Products containing soda and ilica ip gp grmethods have been found to be extravagant in 15 tions of from abdfit one tg two (1Ia20,2iQ t the use of such agents and/or deficient in proaboutmnetoMOASiOZi cedure for effective control of the initial setting.

' Mme or sodium It is also true that previous methods in the use silicate solution of commerce is made by digestof the neutralizing agent have been accompanied ing solid sodium silicate glass with water at eleby the disadvantage of appreciably lower ulti- 20 rated temperatures and pressures. mate tensile strength and ultimate crushing The sodium silicate solutions are slightly un- Strengthstablam-silicaw taking t has n proposed heretofore to p o- Pl e with the production of sodium hydroxide mote hydrolysis and thus accelerate hardening 5 (NaOH) and ta-sili ic acid (HzSiOs). The ough the ad the sodium silicate of meta-silicic acid in turn decomposes to form suBst'ances cap e neutralizin 503511111 water and silica (SiOz), and decomposition of fiydl'me '-D d1 b T0 ACeOr e the meta-silicate with the production of silica to the heretofore customary practicesiamolmts (S102) ultimately results in precipitation of the of neutralizin a e s in excess of the amounts dissolved silica of the water-glass. theoretically required to neutralize all of the so- 30 The tendency of the meta-silicate to hydrolize dium hydroxide which may be produced by hyis retarded as the point of equilibrium is apdrolysis of the meta-silicate have been employed. proached unless through some agency the sodium The use of the heretofore DI D W hydroxide is converted to some other form. If amounts of neutralizing agents results in uncgn;

the sodium hydroxide is converted then the hytx geiinmaliettinaandtheiormfifinomodhfifi drolysis can proceed. The silica (SiOz) is preucts of relatively low ultimate strength as aresult cipitated in the form of an adherent gel which of too rapid setting or hardening and/or because gradually hardens, the water produced disapof the incorporation of excessive amounts of unpearing by evaporation. If water-glass or sodesirable soluble reaction products. On the dium silicate solution is confined beyond the inother hand, the normal rate of setting or harden- 40 fluence of dehydration and chemical factors, ing of sodium silicate adhesives and cements is equilibrium will be reached through slight hyso slow as to prevent continuity of construction drolysis and hardening will never take place. of masonry or other articles of manufacture at If the confinement is not quite complete, as in practical rates. It is desirable so to control the case of cast masses for monolithic purposes initial setting and subsequent hardening that 45 or as in the mortar of brick work, it is possible articles or structures of substantially unimpaired for the hydrolysis to proceed only at a very slow strength may be produced at practical rates. rate dependent upon the very slow neutralization We have found that the initial setting and subof the sodium hydroxide which might be derived sequent hardening can be controlled through the from the carbon dioxide of the air or other neucontrolled use of agents capable of neutralizing 50 tralizing agents which happen to be present in sodium droxide 1n amoun s ess an e the environment. Furthermore, hardening in amounts theoreticall re uired to neu't'rahz' e ail such cases will be quite haphazard depending of the sddium hydi' oxi'd e which may he proupon such factors as humidity, temperature and duced By 5550151515 of the meta-silicate. Other water absorbing capacity of the environment. It agencies such as carbon dioxide of the air proba- 55 bly aid in completing the reactions, and hardeningisaie y the atmosphere and materials and the humidity of the atmosphere are important factors to be considered in determining the amount of any neutralizing agent to be employed.

We have found that at temperatures above about 70 F., when the relative humidity is lower than about 40%, the use of an amount of neutralizing agent equal to about or less, of the theoretically required amount permits the production of structures and articles of high ultimate strength at satisfactory rates. At lower normal working temperatures and higher humidities similar results may be accomplished by increasing the amount of neutralizing agent up to about of the amount theoretically required.

We have also found that variations in temperature and humidity may be compensated for through the use of combinations of neutralizing agents. Thus, for example, at temperatures above about 70 F., when the relative humidity is lower than about 40%, we have employed an amount of dium fluosilicate equal to about 30% of the amount theoretically required, and at temperatures below about 70 F. or when the relative humidity has varied between 40% and 90% we have achieved similar results by substituting 30 WM 1 a fluosilicate for about %to33%o -es um uos e,stillemploying not more than about 30% of he amount of neutralizing agent theoretically required.

In forming the products of our invention, we prefer to employ, as neutralizing agents, fi msili; gates, such, for example, as the alkali metal fluosilicams and the fiuosilicates of barium an ea The reactions resulting from the use of sodium fluosilicate may be represented as follows:

One of the final products of the reactions illustrated above is sodium fluoride (NaF) which is soluble and, therefore, undesirable in an acid proof composition. Owing to the fact, however, that only relatively smal ounts of so m flunsilinatfia e employed in forming the products of our invention, the amounts of sodium fluoride present in the Willi-mum and no serious defects are occasioned thereby. The total amounts of soluble substances in final products to be exposed to the action of sulphuric acid may be reduced by employing fluosilicates of lead and barium which form insoluble sulphates.

Among the factors to be considered in determining the fluosilicate to be employed are the market price and availability of the fluosilicate and the type of end product resulting from its use. The cost of the reagent may be prohibitive or shipping difliculties may be encountered, or the end products of the reactions may be compounds which crystallize with disruptive force or which decompose to create gases which result in the creation of porous structures. Thus, for example, the useof fluosilicic acid (HaSiFs) is objectionable in mos oca lOIlS ecause of the expense and inconvenience of shipping. While ammonium fluosilicate appears to offer the advantage a l s ammoma constituent would ultimately be eliminated from the final structure by gasification in some form, there is the objection that imcontrolled liberation of gas might result in the production of a porous structure. If porous structures are not objectionable, the ammonium compound may be employed. Certain metals form salts with acids which acquire water of crystallization with a resulting increase in volume. Thus, the use of 1magnesium fluosilicateI would be und sirable in e pro uc n o a com ositi to E used in contact with sulphuric acid. nesium fluoride in the final product would e converted to mag esiurn sulphate which crystallizes with seven molecules of water. The crystallization is accompanied by great increase in volume and the force exerted is tremendous. The crystallization of even small quantities would be sufficient to disrupt what otherwise would be a sound structure.

The controlled use of neutralizing agents of our invention may be employed to particular advantage in the production of mortars for laying brick and for the production of plastic masses for filling, backing, brick making, vats, e plaques, etc. All? THE type of aggregate or filler to be used in producing any article or structure will depend upon the u e single??? structure is ed. All commonly employed acid-proof fillers suc as thos ijfiiitainingsillca'may be employed. The particle size of the filler will be overned by ese 0 e ms ed productr" e different amounts of grains of different sizes should be so proportioned as to produce a structure of the desired density.

We have employed finel divided sili a in the following proportions WW to particle sizes as fillers for producing acid proof mortar and for producing plastic masses for backing, filling and shaping in moulds and forms:

. .Filler A (for mortars for laying brick) Screen analysis Cumulative Percent percent Screen mesh Filler B (for mortars ,for filling, backing, moulding, etc.)

Screenanalysis Cumulative Screen mesh Percent percent It is to be understood that the above examples are cited merely as illustrations, and they are not to be considered as limitations.

Qoarse finer; generally require the use of sma er amounts of sodium silicate solutions and correspondingly smaller amounts of neutralizing COATING OR PLASTIC.

agents. We have found that, in employing fine and coarse fillers of the types of Fillers A and B above, amounts of neutralizing agents equal to not more than about 2% and not more than about 1.0%, respectively, of the weights of the fillers produce satisfactory results with the amounts of sodium silicate required to produce suitably plastic masses. Sodium silicate solutions of any suitable compositions may be employed. The relative weights of neutralizing agents and sodium silicate solutions employed will, of course, vary in accordance with the com- 1 positions of the sodium silicate solutions.

The following examples illustrate acid proof compositions formed in accordance with our invention and temperature and humidity conditions under which they may be employed advantageously:

barium fiuosilicate in total amount less than the theoretical amount required to react completely with the sodium hydroxide of the sodium silicate solution.

4. Acid-proof mortar comprising sodium silicate solution, a filler, and two or more fiuosilicates including an alkali metal fiuosilicate and lead fluosilicate in total amount less than the theoretical amount required to react completely with the sodium hydroxide of the sodium silicate solution.

5. Acid-proof mortar consisting of sodium silicate solution, filling material, and one or more neutralizing agents including at least one fluosilicate of an element capable of forming an insoluble salt of the acid, the total amount of neutralizing agent being less than the theoretical amount required to neutralize all of the sodium Example I III IV V VI VII III Fillen. A A

A A B B B B TemperaturafF. (see note #2).-- u... Relative humidity, (see note #3) 60 to 70 Below 40 Over 70 Below 40 40 About 60 Abo Over 70 Below 40 0 40 to Over 0. to 60 to 70 50 70 40 Below 40 Nora l.'lhe examples are for a water glass solution with sp. gr. of 1.33, of sodium silicate corresponding to Nero-3.3 fljfl The amounts given in the examples may be varied plus or minus according to the working consistency desired for the mix N011: 2.-The temperature referred to is that of the materials and air, or such as would prevail in the mortar, etc. during the first hour after application.

Nora 3.The humidity referred to is that ol the air i the environment of the structure while it is being constructed.

Mortars of the type set forth in Exam les I and IV will set sufliciently in twentyto minutes that bricks will not creep wheri the courses are laid above. In eight hours they be well set and quite hard and in twentyhours very hard. In thirty to sixty days, t will have tensile strengths of approximately 0 thousand pounds per square inch and crushing strengths of about six to seven thousand pounds per square inch. Mortars or plastic moulding masses of the type set forth in Examples V to VIII also set within relatively short periods and form structures having high ultimate strengths. Both types of mortars adhere well to iron, wood, etc. and may be used advantageously for forming protective coatings.

We claim:

1. Acid-proof mortar comprising sodium silicate solution, a filler, and one or morefluosilicates including barium fiuosilicate in total amount less than the theoretical amount required to react completely with the sodium hydroxide of the sodium silicate solution.

2. Acid-proof mortar comprising sodium silicate solution, a filler, and one or more fluosilicates including lead fluosilicate in total amount less than the theoretical amount required to react completely with the sodium hydroxide of the sodium silicate solution.

3. Acid-proof mortar comprising sodium silicate solution, a filler, and two or more fluosilicates including an alkali metal fiuosilicate and ext ill hydroxide which might be produced by hydrolysis of the meta-silicate of the sodium silicate solution.

6. Acid-proof mortar consisting of sodium silicate solution, filling material, and one or more neutralizing agents including at least one fiuosilicate of an element capable of forming an insoluble salt of the acid, the total amount of neutralizing agent being not substantially greater than about 40% of the theoretical amount required to neutralize all of the sodium hydroxide which might be produced by hydrolysis of the meta-silicate of the sodium silicate solution.

7. Acid-proof mortar consisting of sodium silicate solution, filling material, and one or more neutralizing agents including at least one fluosilicate of an element capable of forming an insoluble salt of the acid, the total amount of neutralizing agent eing not substantially greater than about 30% f the theoretical amount required to neutralize all of the sodium hydroxide which might be produced by hydrolysis of the meta-silicate of the sodium silicate solution.

8. Acid-proof mortar consisting of sodium silicate solution, filling material, and one or more fiuosilicates in total amount equal to 30 to 40% of the theoretical amount required to neutralize all of the sodium hydroxide which might be produced by hydrolysis of the meta-silicate of the sodium silicatesolution.

CHARLES R. KUZELL. JOHN R. MARSTON. FRANCIS K. MOONEY. 

